DUBLIN NATUEAL HISTOEY SOCIETY. 79 



rVo 5 t)readth, -^^^ to 



Plate II., fig. 11, front view; fig. 12, side view ; fig. 13, end view ; 

 14 and 15, dividing fronds. All magnified 400 diameters. 



Affinities and Difi'erences : — The very minute size, combined with 

 the obtuse, shallow, but decided constriction, and, above aU, the outer 

 margin of each segment being bordered by the minute, opaque or dark 

 granules, render this little species very distinct, causing it to be almost 

 unnecessary to compare it with any other. '^- It is intermediate in size 

 between C. lioculatum and C. tinctum; but, besides the tubercles, it is 

 qaite distinct from them by its broader isthmus and more broadly elliptic 



Genus — Staukastrum {Meyen). 

 Staurastrum lanceolatum (sp. nov.) 



Specific Characters : — Frond minute ; segments smooth, broadly lan- 

 ceolate, extremities acute, minutely apiculate ; end view, triangular, 

 angles minutely apiculate, sides concave. 



Locality : — Sphagnum ponds, Featherbed bog, county of Dublin, 

 coating the moss. 



General Description : — Frond minute, about as broad as long, con- 

 striction forming a deep acute notch at each side ; supposing the con- 

 striction absent, the frond would present an orbicular outline ; segments 

 smooth, in front view broadly lanceolate, the outer margin slightly more 

 convex than the inner, their opposite lateral extremities acute, minutely 

 apiculate (though the apiculus is sometimes difficult of detection) ; end 

 ■vaew triangular, angles somewhat inflated, minutely apiculate, sides con- 

 cave at the centre. Sporangium orbicular, spinous ; spines numerous, 

 somewhat inflated at the base, their extremities subulate, acute. 



Measurements : — Length of frond, yo\jg ; breadth, 

 of sporangium, including spines, -g-^ 

 inch. 



Plate II., fig. 16, front view; fig. 17, angular view; fig. 18, end 

 view. All magnified 400 diameters. 



Affinities and Differences : — This species agrees somewhat with Stau- 

 rastrum orhiculare (Ralfs) in its general external outline ; but it diflers 

 therefrom in its segments being lanceolate, not semiorbicular (the con- 

 striction being not linear, but a gaping notch), and in the opposite lateral 

 extremities not being rounded, but acute and apiculate. Its lanceolate 

 apiculate segments separate it from S. muticum (Breb.) The same cha- 

 racters separate it from S.pygmceum (Breb.), which latter has cuneiform 

 segments, as well as the extremities of the spines of the sporangium 

 being bifurcate, not subulate and acute, as in this species. From S. de- 



* Unfortunately the figures (Fig. 11-14) are incorrect in representing the tubercles as 

 so large and elevated. They do not stand out, nor do they appear of the nature of the 

 " pearly granules" of other species. They are more minute, less elevated, and more 

 opaque than in the figure. 



